Automatic white balancing method, medium, and system

ABSTRACT

A white balancing detecting method, medium, and system. The white balancing method includes setting an illuminant detection region of an input image in accordance with an exposure integration time indicative of a collected amount of light when the image is taken, and detecting an illuminant by using data contained in the illuminant detection region in a color gamut of the image.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority from Korean PatentApplication No. 10-2006-0047751, filed on May 26, 2006 in the KoreanIntellectual Property Office, the disclosure of which is incorporatedherein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

One or more embodiments of the present invention relate to a colorreproduction technology, and more particularly, to a white balancingmethod, medium, and system.

2. Description of the Related Art

Though natural Light is typically thought of as being white, inactuality the light may have an abundance of one or more wavelengthsresulting in the overall light having a peculiar color called a colortemperature, expressed in Kevin (K). In general, since the human beings'visual ability automatically adjusts for such minor discrepancies, thehuman beings' cognitive difference for the colors is very insignificanteven though light of a particular color temperature may be illuminated.However, image pick-up devices, such as a camera or a camcorder, sensecolors, in which color temperatures are reflected, as they are.Accordingly, if an illuminant is changed, images taken by the imagepick-up device are tingled with different colors.

For example, since the color temperature of sunlight around noon on asunny day is considered to be high, the image taken by an image pick-updevice will appear bluish on the whole. By contrast, since the colortemperature of the sunlight just after sunrise or just before sunset isconsidered to be low, the image taken by the image pick-up device willappear reddish on the whole.

An auto white balancing (AWB) technique proposed to solve this problemcompensates for distortions of the color tone of the image if the imageis deflected toward any one of red (R), green (G), and blue (B)components depending upon its color temperature.

In one example, an image pick-up device discussed in Japanese PatentUnexamined Publication No. 2002-290988, divides an object into aplurality of regions, detects chromaticity in every region having aluminance higher than a threshold value, and calculates a gain value toperform white balancing based on the detected chromaticity.

However, such white balancing techniques have problems in that it isdifficult to perform a consistent color reproduction in accordance withthe color or dimension of an object existing in the image even thoughthe image is taken under the same light source or illuminant.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made to solve suchabove-mentioned problems, with an aspect of one or more embodiments ofthe present invention being to improve the performance of colorreproduction through a more stable illuminant estimation.

Additional aspects and/or advantages of the invention will be set forthin part in the description which follows and, in part, will be apparentfrom the description, or may be learned by practice of the invention.

To achieve the above and/or other aspects and advantages, embodiments ofthe present invention include a method with white balancing, includingsetting an illuminant detection region of an image based on an exposureintegration time indicative of an amount of light collected for theimage when the image was captured, and detecting an illuminant of theimage by using data relative to the illuminant detection region in acolor gamut of the image.

To achieve the above and/or other aspects and advantages, embodiments ofthe present invention include at least one medium including computerreadable code to control at least one processing element to implementone or more embodiments of the present invention.

To achieve the above and/or other aspects and advantages, embodiments ofthe present invention include a system, including a setting unit to setan illuminant detection region of an image based on an exposureintegration time indicative of an amount of light collected for theimage when the image was captured, and a detection unit to detect anilluminant of the image by using data relative to the illuminantdetection region in a color gamut of the image.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will becomeapparent and more readily appreciated from the following description ofthe embodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 illustrates a white balancing system, according to an embodimentof the present invention;

FIG. 2 illustrates a white balancing method, according to an embodimentof the present invention;

FIG. 3 illustrates an illuminant detection region, according to anembodiment of the present invention;

FIG. 4 illustrates a candidate region that can be set as an illuminantdetection region, according to an embodiment of the present invention;

FIGS. 5A through 5C are illustrations explaining a setting of anilluminant detection region, according to an embodiment of the presentinvention;

FIGS. 6A through 6E are illustrations explaining an obtaining ofvariation of color gamut and a central point, according to an embodimentof the present invention;

FIG. 7 illustrates a detection unit, according to an embodiment of thepresent invention;

FIG. 8 illustrates an operation of a division unit, according to anembodiment of the present invention;

FIG. 9 illustrates an operation of a comparative value determinationunit, according to an embodiment of the present invention;

FIG. 10 is an illustration explaining the inconsistency between theilluminant distribution probability and a reference illuminant locusaxis;

FIG. 11 illustrates a correcting of an illuminant, according to anembodiment of the present invention; and

FIGS. 12A and 12B are illustrations explaining a correcting of anilluminant, according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. Embodiments are described below to explain the presentinvention by referring to the figures.

FIG. 1 illustrates a white balancing system 100, according to anembodiment of the present invention. The white balancing system 100 mayinclude a setting unit 110, a detection unit 120, a stabilization unit130, and a white balancing unit 140, for example. In differingembodiments, the white balancing system may be an image processingsystem such as a digital still camera, a digital video camcorder, andothers, for example.

In addition, white balancing operations illustrated in FIG. 2 will bedescribed with reference to the white balancing system 100, noting thatthe reference to the white balancing system 100 is merely used as anexample for instructive purposes. The setting unit 110 may set anilluminant detection region for an input image, for example, inoperation S210, e.g., by selectively using an exposure integration time(EIT) as a reference to determine the illuminant detection region. TheEIT means a time required for collecting light when photographing/takingan image. However, the EIT is not limited to a temporal element, and maybe determined by other information which can predict a collected amountof the light when the image is photographed/taken. More specifically,for example, the EIT may be determined by exposure information such as ashutter speed or an aperture value.

The EIT may also be provided together with an image to be input eitherat the time of the image photographing of the image or stored with orfor the image for subsequent correction. For example, as the digitalstill camera attaches the exposure information at the time of thephotographing of the image, such as shutter speed or aperture value, tothe photographed image as additional data, the EIT may be attached tothe image file, or imbedded in the image, as the additional data.

Meanwhile, the illuminant detection region represents a range of data tobe used to detect an illuminant of the image, an example of which isshown in FIG. 3. The detection unit 120 may detect the illuminant byusing data to be contained in an illuminant detection region 320, whichmay be set by the setting unit 110, in a color gamut 310 of the image,for example, in operation S220.

The illuminant detected by the detection unit 120 may reflect distortedinformation, e.g., in accordance with a deviation between devices or anamount of data sampled for detecting the illuminant, such that thestabilization unit 130 may further correct the detected illuminant so asto correct the distorted information, for example, in operation S230.

The white balancing unit 140 may further perform white balancing on theimage by use of the corrected illuminant, for example, in operationS240. Since there are diverse known techniques for performing the whitebalancing on the image, the detailed description thereof will be omittedherein.

The example operation of setting the illuminant detection region for theinput image can be performed by the setting unit 110 in FIG. 1, and cancorrespond to the operation S210 of FIG. 2, for example, noting thatalternative operations and units for accomplishing the same are equallyavailable.

As described above, the setting unit 110 may set the illuminantdetection region associated with the EIT. In an embodiment, bystatistically analyzing the relationship between the EIT consumed whenthe image is taken and the point, in which the illuminant exists, in thecolor gamut of the taken image, any of the candidate regions 410 through440 having a high possibility that the illuminant exists may bepreviously set in accordance with the EIT, as shown in FIG. 4. Forexample, if the EIT of the input image belongs to a range of 0 to N1,the setting unit 110 may set the first candidate region 410 as theilluminant detection region. Meanwhile, if the EIT of the input imagebelongs to a range of N1 to N2, the setting unit 110 may set the secondcandidate region 420 as the illuminant detection region. Other candidateregions 430 and 440 may be set as the illuminant detection regionassociated with the EIT of the input image.

According to the embodiment shown in FIG. 4, the candidate regions 410through 440 may be fixed on chromaticity coordinates, and any one of thefixed candidate regions determined as the illuminant detection region.However, embodiments of the present invention are not limited thereto.For example, an alternative embodiment may be implemented which performsmodeling of the point, in which the illuminant of the image exists, onthe chromaticity coordinates in accordance with the EIT, and variablysets the illuminant detection region in accordance with the EIT of theinput image. Such an embodiment will now be described in detail withreference to FIGS. 5A through 5C.

FIG. 5A illustrates chromatic values of illuminants of respective imagesassociated with respective EITs. Such information may be obtainedthrough previous experiments or during operation of a respective cameradevice or white balancing system.

From such information, a modeling of a median chromaticity locus of theilluminant associated with the EIT can be performed. To this end, anaverage chromatic value of the illuminants corresponding to each EIT canbe calculated, and a trend line 510 of the points representing eachaverage chromatic value can be obtained. The obtained trend line canfurther be projected on the chromaticity coordinates to obtain themedian chromaticity locus 520 of the illuminant, as shown in FIG. 5B.

The illustrated median chromaticity locus 520 of the illuminantassociated with any particular EIT may not be previously set, and thesetting unit 110 can obtain the central illuminant point correspondingto the EIT of the image to be input from the median chromaticity locus520 of the illuminant.

In an embodiment, if the central illuminant point is obtained, thesetting unit 110 may then set a given range as the illuminant detectionregion 540 based on the central illuminant point 530, as shown in FIG.5C. In one embodiment, the illuminant detection region 540 can be setfrom the central illuminant point 530 to the first threshold distance550 in the median chromaticity locus 520 of the illuminant, and to thesecond threshold distance 560 in a direction perpendicular to the medianchromaticity locus 520 of the illuminant. Herein, the first thresholddistance and the second threshold distance may be set in accordance withthe tendency of the chromaticity distribution of the illuminantassociated with the EIT, which again may be previously determined byexperiment or previous operation.

The first threshold distance and the second threshold distance may bedetermined dynamically in accordance with the EIT. For example, if it isassumed that when the EIT is low, the chromaticity distributed range ofthe illuminant is narrow, while when the EIT is high, the chromaticitydistributed range of the illuminant is wide, at least one of the firstthreshold distance and the second threshold distance may be altered inaccordance with the EIT, so as to reflect this observed tendency. Here,alternate tendencies may also be observed depending on embodiment.

According to one embodiment, the setting unit 110 may additionally use avariance of the color gamut of the image to be input and the centralpoint of the color gamut, so as to set the illuminant detection region,as shown in FIG. 6A.

In order to obtain the variance of the color gamut, the setting unit 110may select the illustrated threshold number of data 610-1 through 610-4in near order from four reference points O, P, Q, and R on thechromaticity coordinates in the color gamut of the image to be input.

The four reference points, according to an embodiment of the presentinvention, include, as shown in FIG. 6B, an origin O (0, 0) of thechromaticity coordinates, a point P (Cr-max, 0) indicative of themaximum Cr value, Cr-max, which can be possessed by a general image on aCr-axis, a point Q (Cb-max, 0) indicative of the maximum Cb value,Cb-max, which can be possessed by a general image on a Cb-axis, and acoordinate point R (Cr-max, Cb-max) indicative of the maximum Cr valueand the maximum Cb value.

FIG. 6C illustrates four such reference points, according to alternativeembodiment of the present invention, with two reference points O (0, 0)and R(Cr-max, Cb-max) among four reference points being similar to thoseof the embodiment in FIG. 6B. However, the other two reference points Pand Q are cross points formed by the axes of two chromaticitycoordinates and an extension of the reference illuminant locus 620. Thereference illuminant locus 620 means a trend line based on thechromaticity of diverse types of standard illuminants (e.g., D65, D50,CWF (Cool White Fluorescent), A, Horizon, and others) which are properto characteristics of a device (e.g., a digital still camera including awhite balancing system 100) capturing an image.

As illustrated in FIG. 6D, if the threshold number of data is selectedin near order from each reference point, the setting unit 110 maydetermine edge points 630-1, 630-2, 630-3, and 630-4 having the averagechromatic value of the data every selected data through each referencepoint.

After that, as illustrated in FIG. 6E, the setting unit 110 maycalculate a distance between the edge points derived from the diagonalreference points among four reference points. That is, the setting unit110 may calculate a distance 640 (referred to as a color gamut height)between the edge point 630-1 derived from the reference point O and theedge point 630-4 derived from the reference point R, and a distance 650(referred to as a color gamut width) between the edge point 630-2derived from the reference point P and the edge point 630-3 derived fromthe reference point Q.

Then, the setting unit 110 may determine whether the color gamut height540 and the color gamut width 650 exist in a given threshold range,respectively. If the color gamut height 540 and the color gamut width650 satisfy the given threshold range, the setting unit 110 may use theilluminant detection region determined in accordance with the EIT as itis, since it may be considered that the input image has a normal colordistribution. However, if the color gamut height 540 and the color gamutwidth 650 are found to be outside of the threshold range, it can beunderstood that the input image has an abnormal color distribution,since the color gamut of the input image is excessively wider ornarrower than a normal case. In this instance, where the color gamutheight 540 and the color gamut width 650 are outside of the thresholdrange, if a portion of the color gamut of the input image were to bedetermined to be the illuminant detection region in accordance with theEIT, there is a high possibility that the correct illuminant would notbe detected. Accordingly, the setting unit 110 can set the color gamutof the input image as the illuminant detection region irrespective ofthe EIT, such as through conventional techniques, after such a detectionthat the color gamut height or the color gamut width is out of thethreshold range.

Since the variance of the color gamut indicates the uniformity of thecolor gamut, embodiments of the present invention are not limited to theabove described methods of calculating the variance of the color gamut.For example, the setting unit 110 may select the threshold number ofdata in the color gamut of the input image in near order from fourreference points, and predict the variance of the color gamut by use ofthe distance between the points having the mean chromaticity of theselected data. Alternate methods are also available.

Returning to FIG. 6E, in another embodiment, the central point of thecolor gamut can be determined as a cross point 660 of a segmentrepresenting the color gamut height and the color gamut width. Thesetting unit 110 may determine whether the use of the illuminantdetection region determined in accordance with the EIT is appropriatethrough the central point 660 of the color gamut.

For example, modeling can be performed of the point, on which theilluminant of the image exists, on the chromaticity coordinates inaccordance with the central point 660 of the color gamut, similar to themethod of modeling the point, on which the illuminant of the imageexists, on the chromaticity coordinates in accordance with the EIT. Thatis, the point, on which the illuminant of the image can exist, may beset as a desired number of regions on the chromaticity coordinates inaccordance with the central point 660 of the color gamut.

Then, it can be determined whether the use of the illuminant detectionregion determined by the EIT is appropriate, through whether the regionon the chromaticity coordinates corresponding to the central point 660of the color gamut of the input image overlaps the illuminant detectionregion determined in accordance with the EIT. If the region on thechromaticity coordinates corresponding to the central point 660 of thecolor gamut is identical or sufficiently similar to the illuminantdetection region determined by the EIT, the illuminant detection regiondetermined by the EIT can be used as it is. However, if the region onthe chromaticity coordinates corresponding to the central point 660 ofthe color gamut is not identical or sufficiently similar to theilluminant detection region determined by the EIT, the color gamut ofthe input image can be set as the illuminant detection regionirrespective of the EIT.

An operation of detecting the illuminant may, thus, be performed by thedetection unit 120 in FIG. 1, for example, and may correspond tooperation S220 in FIG. 2, also for example, noting that alternativeoperations and units for accomplishing the same are equally available.The detection unit 120 may include, as shown in FIG. 7, a division unit710, a comparative value determination unit 720, and an illuminantestimation unit 730, for example.

The division unit 710 may divide the data contained in the illuminantdetection region, e.g., as set by the setting unit 110 in the colorgamut of an input image, into two groups on the basis of luminance. FIG.8 illustrates an example operation of the division unit 710, noting thatalternative operations and units for accomplishing the same are equallyavailable.

In reference to FIG. 8, an average luminance value and a mean luminancevalue of the data contained in the illuminant detection region may becalculated, in operation S810. Threshold number of data (referred to assuperior luminance data) may be further sorted in order of highluminance value among luminance distribution of the data contained inthe illuminant detection region, and the same number of data as that ofthe superior luminance data in order of low luminance value. In anembodiment, the average luminance value Y_(thresh) may be calculatedfrom a mean between an average value of the luminance values of theupper luminance data and an average value of the luminance values oflower luminance data. In addition, the mean luminance value Y_(avg) maybe calculated by an average of the luminance values of all datacontained in the illuminant detection region.

Then, a threshold luminance value may be calculated to be used to dividethe data in the illuminant detection region into two groups by using theaverage luminance value and the mean luminance value, in operation S820.The threshold luminance value may be determined by a weighted sum of theaverage luminance value of the data contained in the illuminantdetection region and the mean luminance value thereof, which may beexpressed by the below Equation 1, for example.Y _(thresh) =k·Y _(median)+(1−k)·Y _(avg)   Equation 1:

Here, Y_(thresh) is a threshold luminance value to be calculated,Y_(median) is a median luminance value, and Y_(avg) is an averageluminance value. In addition, k may be a weighted value of 0 or 1, forexample.

If the threshold luminance value is calculated, the data in theilluminant detection region may be divided into two groups on the basisof the threshold luminance value, in operation S830. For example, thedata having a luminance more than a threshold luminance value among thedata in the illuminant detection region may be classified into the firstgroup, and the data having a luminance less than a threshold luminancevalue may be classified into the second group.

The comparative value determination unit 720 in FIG. 7 may set acomparative illuminant to be a standard of determining the illuminant.FIG. 9 illustrates an example operation of the comparative valuedetermination unit 720, noting that alternative operations and units foraccomplishing the same are equally available.

In reference to FIG. 9, an average may be calculated of an averagechromatic value of the data contained in the illuminant detection regionand a mean chromatic value thereof, in operation S910. Here, forexample, the average chromatic value may be calculated by the average ofthe chromatic values of the data contained in the illuminant detectionregion, and the median chromatic value may be calculated by a chromaticvalue of the center point of the illuminant detection region.

Then, a weighted average may be calculated of the average chromaticvalue and the median chromatic value, in operation S920, as expressed bythe below Equation 2, for example.Ch _(w) =m·Ch _(avg)+(1−m)·Ch _(median)   Equation 2:

Here, Ch_(w) is a weighted average to be calculated, Ch_(avg) is anaverage chromatic value, and Ch_(median) is a median chromatic value. Inaddition, m may be a weighted value of 0 or 1, for example.

An average may be calculated of chromatic values of the data containedin each of two divided groups, e.g., as divided by the division unit710, in operation S930. Hereinafter, the average of the chromatic valuesof the data contained in the first group will be referred to as thefirst average, and the average of the chromatic values of the datacontained in the second group will be referred to as the second average.

A difference value may further be calculated between the first averageand the second average, in operation S940. Next, a comparativeilluminant may be set by using the weighted average Ch_(w), e.g.,calculated in the operation S920, the difference value, e.g., calculatedin the operation S940, and a standard illuminant (e.g., D65, D50, CWF,A, Horizon, and the others) of a device providing a corresponding imageframe (e.g., a digital still camera comprising the white balancingsystem 100) as an input value, in operation S950. In order to obtain thecomparative illuminant, the below Equation 3 may be used, for example.W _(ref)(r,b)=F ₂(F ₁(Ch _(w) ,DEV _(w)),Ch _(dist))   Equation 3:

Here, W_(ref)(r,b) is a chromatic value of the comparative illuminant,Ch_(w) is a weighted average calculated in operation S920, for example,DEV_(w) is a standard illuminant, and Ch_(dist) is a difference valuebetween the first average and the second average calculated in theoperation S940, for example. In addition, F1 may be a quadraticcorrelation function, and F2 may be a linear correlation function.

The correlation function F1 may be a function reflecting a correlationbetween the standard illuminants and Ch_(w) under the standardilluminant, and a substantial comparative estimating function toestimate the point of the illuminant in the image, for example. Thecorrelation function F2 may be a modeling function considering Ch_(dist)in the standard illuminant locus function, and a function to compensatea performance of a comparative illuminant estimation of the correlationfunction F1, for example.

The order of functions F1 and F2 can be varied, and F1 and F2 may be setas a quadratic function and a linear function, respectively, as oneexample of optimizing its complexity. A concrete embodiment of F1 and F2can be easily understood through the below Equations 4 through 6, forexample.Σ(|DEV _(w) −α*Ch _(w) ² −β*Ch _(w)−γ|)≅0   Equation 4:F ₁ =α*Ch _(w) ² +β*Ch _(w)+65   Equation 5:F ₂=θ*(F ₁(Ch _(w) ,DEV _(w))±Ch _(dist))+ζ  Equation 6:

Here, in Equations 4 through 6, α, β, γ, θ, and ζ are a certain realnumber, and may be determined as a proper value based on experimentresults. For example, α, β, and γ may preferably exist as in therelation in Equation 4, noting that alternative embodiments are equallyavailable.

Referring again to FIG. 7, in identifying the initial illuminant, theilluminant estimation unit 730 may determine the point, in which achromatic difference between the comparative illuminant, e.g., asdetermined in the above operation S950, and any one of the first averageand the second average, e.g., as calculated in the above operation S940,as the initial illuminant. That is, the illuminant estimation unit 730may calculate a chromatic difference (referred to as first chromaticdifference) between the first average and the comparative illuminant,and a chromatic difference (referred to as second chromatic difference)between the second average and the comparative illuminant, and comparethe first chromatic difference and the second chromatic difference. Ifthe first chromatic difference is smaller than the second chromaticdifference, the first average may be determined to be the initialilluminant, while if the second chromatic difference is smaller than thefirst chromatic difference, the second average may be determined to bethe initial illuminant.

With reference to FIG. 10, distorted information may be reflected in theilluminant detected by the detection unit 120 in accordance with thedeflection between devices providing the image or an amount of datasampled to detect the illuminant. For example, if the illuminant isdetected according to the data contained in the illuminant detectionregion, the position of the illuminant detection region may bedetermined to be in the specified range in accordance with the EIT, butthe amount of data or the chromaticity information to be input into theilluminant detection region may be varied depending upon thechromaticity variation of the device providing the image. In thisinstance, since the illustrated probability distribution 1020 in whichthe illuminant information exists in the illuminant detection region1010 may not conform to the reference illuminant locus axis 1030, itbecomes desirable to provide a new illuminant locus axis 1040 byadjusting the reference illuminant locus axis 1030.

In order to compensate this distortion phenomenon, the stabilizationunit 130, for example, may stabilize the initial illuminant detected bythe detection unit 120 based on the reference illuminant locus and theaverage chromatic value of data input into the illuminant detectionregion in the color gamut of the input image. FIG. 11 illustrates anexample operation of the stabilization unit 130, noting that alternativeoperations and units for accomplishing the same are equally available.

In reference to FIG. 11, the stabilization unit 130 may calculate aweighted average point between the average chromatic value of data inputinto the illuminant detection region in the color gamut of the image andthe chromatic value of the initial illuminant, in operation S1110. Theweighted average may be expressed by the below Equation 7, for example.W _(avg) =N·W _(i)+(1−N)·Ch _(avg)   Equation 7:

Here, W_(avg) is a weighted value to be calculated, W_(i) is a chromaticvalue of the initial illuminant, e.g., as determined by the illuminantestimation unit 730, and Ch_(avg) is an average of chromatic values ofthe data contained in the illuminant detection region. Ch_(avg) is alsoused in Equation 2. In addition, N may be a weighted value of 0 or 1,for example.

As shown in FIG. 12A, a new illuminant locus 1230 which contains aweighted average point 1210 and is parallel with the referenceilluminant locus 1220 may then be set, in operation S1120.

Further, as shown in FIG. 12B, a point 1250 in which the initialilluminant 1240 is projected on the new illuminant locus 1230 in avertical direction may be determined, in operation S1130.

In embodiments of the present invention, the term “unit” indicating arespective component of the white balancing system 100, for example, maybe constructed as a module, for example. Here, the term “module”, asused herein, means, but is not limited to, a software and/or hardwarecomponent, such as a Field Programmable Gate Array (FPGA) or ApplicationSpecific Integrated Circuit (ASIC), which performs certain tasks. Amodule may advantageously be configured to reside on the addressablestorage medium and configured to execute on one or more processors.Thus, a module may include, by way of example, components, such assoftware components, object-oriented software components, classcomponents and task components, processes, functions, attributes,procedures, subroutines, segments of program code, drivers, firmware,microcode, circuitry, data, databases, data structures, tables, arrays,and variables. The operation provided for in the components and modulesmay be combined into fewer components and modules or further separatedinto additional components and modules.

In addition to the above described embodiments, embodiments of thepresent invention can also be implemented through computer readablecode/instructions in/on a medium, e.g., a computer readable medium, tocontrol at least one processing element to implement any above describedembodiment. The medium can correspond to any medium/media permitting thestoring and/or transmission of the computer readable code.

The computer readable code can be recorded/transferred on a medium in avariety of ways, with examples of the medium including recording media,such as magnetic storage media (e.g., ROM, floppy disks, hard disks,etc.) and optical recording media (e.g., CD-ROMs, or DVDs), andtransmission media such as carrier waves, as well as through theInternet, for example. Thus, the medium may further be a signal, such asa resultant signal or bitstream, according to embodiments of the presentinvention. The media may also be a distributed network, so that thecomputer readable code is stored/transferred and executed in adistributed fashion. Still further, as only an example, the processingelement could include a processor or a computer processor, andprocessing elements may be distributed and/or included in a singledevice.

In accordance with the above description, one or more embodiments of thepresent invention include a white balancing method, medium, and system,where the color reproducing performance can be improved through morestabilized illuminant estimation.

Although a few embodiments of the present invention have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in these embodiments without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

1. A method with white balancing, comprising: setting an illuminantdetection region of an image based on an exposure integration timeindicative of an amount of light collected for the image when the imagecaptured; and detecting an illuminant of the image by using datarelative to the illuminant detection region in a color gamut of theimage.
 2. The method of claim 1, wherein the setting of the illuminantdetection region comprises determining a candidate region whichcorresponds to the exposure integration time, from among a plurality ofpredefined candidate regions set in accordance with respective exposureintegration times, as the illuminant detection region.
 3. The method ofclaim 1, wherein the setting of the illuminant detection regioncomprises determining a given range, as the illuminant detection region,from a point corresponding to the exposure integration time in aspecified locus on predefined chromaticity coordinates set based on adegree of illuminant distribution according to respective exposureintegration times.
 4. The method of claim 3, wherein the given range isvariable depending upon the exposure integration time.
 5. The method ofclaim 1, wherein the setting of the illuminant detection region furthercomprises determining the illuminant detection region by using at leastone of a variance of the color gamut of the image and a center point. 6.The method of claim 5, wherein the determining of the illuminantdetection region comprises adjusting the illuminant detection regionbased on whether the variance of the color gamut satisfies a specifiedthreshold range.
 7. The method of claim 1, wherein the detecting of theilluminant comprises: dividing the data relative to the illuminantdetection region into a first group and a second group in accordancewith luminance distribution of the data relative to the illuminantdetection region in the color gamut of the image; and determining atleast one of a first average luminance value of data relative to thefirst group and a second average luminance value of data relative to thesecond group as the illuminant.
 8. The method of claim 7, wherein thedividing comprises dividing the data relative to the illuminantdetection region into the first group and the second group based on athreshold luminance value derived from a weighted sum of an averageluminance value of the data relative to the illuminant detection regionand a median luminance value of the illuminant detection region.
 9. Themethod of claim 7, wherein the determining of the at least one of thefirst average luminance value and the second average luminance valuecomprises determining any one of the first average luminance value andthe second average luminance value as the illuminant, in which when achromatic difference between the first average luminance value and agiven comparative illuminant and a chromatic difference between thesecond average luminance value and the given comparative illuminant arecompared, based on a respective lowest chromatic difference.
 10. Themethod of claim 9, wherein the comparative illuminant is obtained from acorrelation function using at least one among a weighted average valuebetween an average chromatic value of the data relative to theilluminant detection region and a median chromatic value of theilluminant detection region, a difference value between the firstaverage luminance value and the second average luminance value, andstandard illuminant information a system which captured the image, as aninput value.
 11. The method of claim 10, wherein the correlationfunction is a linear correlation function using a resultant value of asub-correlation function and the difference value as an input value, andthe sub-correlation function is a quadratic correlation function usingthe weighted average value and the standard illuminant information as aninput value.
 12. The method of claim 1, further comprising compensatingthe determined illuminant.
 13. The method of claim 12, wherein thecompensating comprises modifying the determined illuminant by setting apoint, in which the determined illuminant is perpendicularly reflectedon a given illuminant locus, as the determined illuminant.
 14. Themethod of claim 13, wherein the given illuminant locus is parallel to atrend line of a plurality of standard illuminants associated with acharacteristic of a system which captured the image, and has a weightedaverage point of a chromatic value of the determined illuminant and anaverage chromatic value of the data relative to the illuminant detectionregion.
 15. The method of claim 1, further comprising performing whitebalancing on the image based on the determined illuminant.
 16. At leastone medium comprising computer readable code to control at least oneprocessing element to implement the method of claim
 1. 17. A system,comprising: a setting unit to set an illuminant detection region of animage based on an exposure integration time indicative of an amount oflight collected for the image when the image was captured; and adetection unit to detect an illuminant of the image by using datarelative to the illuminant detection region in a color gamut of theimage.
 18. The system of claim 17, wherein the setting unit determines acandidate region which corresponds to the exposure integration time,from among a plurality of predefined candidate regions set in accordancewith respective exposure integration times, as the illuminant detectionregion.
 19. The system of claim 17 wherein the setting unit determines agiven range, as the illuminant detection region, from a pointcorresponding to the exposure integration time in a specified locus onpredefined chromaticity coordinates set based on a degree of illuminantdistribution according to respective exposure integration times.
 20. Thesystem of claim 19, wherein the given range is variable depending uponthe exposure integration time.
 21. The system of claim 17, wherein thesetting unit determines the illuminant detection region by using atleast one of a variance of the color gamut of the image and a centerpoint.
 22. The system of claim 21, wherein the setting unit adjusts theilluminant detection region according to whether the variance of thecolor gamut satisfies a specified threshold range.
 23. The system ofclaim 17, wherein the setting unit comprises: a division unit to dividethe data relative to the illuminant detection region into a first groupand a second group in accordance with luminance distribution of the datarelative to the illuminant detection region in the color gamut of theimage; and an illuminant determination unit to determine at least one ofa first average luminance value of data relative to the first group anda second average luminance value of the data relative to the secondgroup as the illuminant.
 24. The system of claim 23, wherein thedivision unit divides the data relative to the illuminant detectionregion into the first group and the second group based on a thresholdluminance value derived from a weighted sum of an average luminancevalue of the data relative to the illuminant detection region and amedian luminance value of the illuminant detection region.
 25. Thesystem of claim 23, wherein the illuminant determination unit determinesany one of the first average luminance value and the second averageluminance value as the illuminant, in which when a chromatic differencebetween the first average luminance value and a given comparativeilluminant and a chromatic difference between the second averageluminance value and the given comparative illuminant are compared, basedon a respective lowest chromatic difference.
 26. The system of claim 25,wherein the comparative illuminant is obtained from a correlationfunction using at least one among a weighted average value between anaverage chromatic value of the data relative to the illuminant detectionregion and a median chromatic value of the illuminant detection region,a difference value between the first average luminance value and thesecond average luminance value, and standard illuminant information of asystem which captured the image, as an input value.
 27. The system ofclaim 26, wherein the correlation function is a linear correlationfunction using a resultant value of a sub-correlation function and thedifference value as an input value, and the sub-correlation function isa quadratic correlation function using the weighted average value andthe standard illuminant information as an input value.
 28. The system ofclaim 17, further comprising a stabilization unit compensating thedetermined illuminant.
 29. The system of claim 28, wherein thestabilization unit modifies the determined illuminant by setting apoint, in which the determined illuminant is perpendicularly reflectedon a given illuminant locus, as the determined illuminant.
 30. Thesystem of claim 29, wherein the given illuminant locus is parallel to atrend line of a plurality of standard illuminants associated with acharacteristic of a system which captured the image, and has a weightedaverage point of a chromatic value of the determined illuminant and anaverage chromatic value of the data relative to the illuminant detectionregion.
 31. The system of claim 17, further comprising a white balancingunit which performs white balancing on the image based on the determinedilluminant.